Caddyfile - How can we do reverse proxy on a single port for multiple server?

Okay, those files are from CDN, so that’s fine. That’s not affected by this.

But if you do have any files that are loaded in the HTML as URLs like /example.css, they will be loaded from the root of your site instead of from /frontend/example.css for example.

But I’m not really clear on what’s not working. What server are you running upstream? Check if there’s any configuration for it where you need to set a “base path” or whatever.